This application claims priority from European patent application EP 09 013 408.1, filed Oct. 23, 2009, and the entire contents of European patent application EP 09 013 408.1 are incorporated herein by reference.
The subject matter of the invention is a process for producing seed crystals for chocolate products, which process comprises the steps of heating cocoa butter or chocolate masses, mixing the heated mass with a supercritical fluid and expanding the solution obtained in an expansion apparatus so that the formation of powder particles takes place and separation of the powder particles from the gas, as well as the use of the seed crystals obtained for the production of chocolate products.
The production of chocolate is a time-intensive process in spite of modern engineering. The most important quality features of chocolate, such as melting properties, breaking quality, consistency and appearance are a function of the crystal structure of the triglycerides of the cocoa butter contained in the chocolate. The chocolate mass is therefore traditionally subcooled in order to form crystals and subsequently melted again in order to obtained the most ideal crystal structures possible. During this “tempering” the liquid chocolate mass is subjected to a controlled series of different temperatures, i.e., to an alternating cooling down and a reheating. The goal here is to obtain as many crystals as possible in the βV form. Cocoa butter crystallizes in 6 different crystal forms that have different melting points between 17.3° C. and 36.3° C. The crystal structures are in the series of rising melting points (according to G. Baler, Lebensmittel-Industrie (that is, “Food Industry”, here and elsewhere) No. 314, 2005, p. 6):
γ0° C. to 18° C.α18° C. to 22.5° C.βIII22.5° C. to 27.5° C.βIV27.5° C. to 29.5° C.βV29.5° C. to 33.5° C.βVI33.5° C. to 37° C.
The crystal forms γ, α, βIII and βIV are semi-stable or not stable, for which reason they are undesired in the production of chocolate. Only the crystal forms βV and βVI, that are also designated in some cases as the β form and the β2 form, have the desired stability. The βVI crystal structure does result in a rapid crystallization and solidification; however, since it feels waxy in the mouth it is undesired. On the other hand, a high proportion of βV crystals (beta five crystals) results in a pleasant melt with a stable crystal form. A high number of βV crystals can be produced by the above-described tempering of the liquid chocolate mass. As a result, the chocolate receives better quality properties regarding appearance, consistency and shelf life. In particular in the case of pralines and filled chocolate products this also prevents a premature migration of fat. The migration of fat can be observed as “fat bloom”. Fat bloom is observed as a whitish coating on the chocolate. Fat bloom is produced by the formation of βVI crystals on the surface.
In order to accelerate the traditional tempering process, in some cases seed crystals are added to the mass during the production of chocolates, preferably before the tempering process. For example, cocoa butter crystals or chocolate crystals are used as seed crystals.
In a few processes a tempering can be eliminated as a function of the dosage of the seed crystals. After the forming, cooling and packaging the products treated in this manner display the properties of a well-tempered chocolate mass. However, it turned out that in as far as the seed crystals are produced by grinding or other mechanical comminuting processes the powdery particles do not have the desired morphology since the surfaces are frequently not intact and as a result even undesired crystal forms are present. There are therefore various attempts to produce seed crystals for the production of chocolate with the aid of non-mechanical processes.
Such a process for the production of seed crystals is described in DE 603 13 210 T2. In it a certain amount of a substance to be treated is dissolved in a supercritical fluid and expanded in a second zone, during which the particles to be crystallized precipitate during the expansion in the first dissolving zone as well as also in the collection zone. However, this process has the disadvantages that only a small amount of the cocoa butter or chocolate mass used is converted into RV crystals. In addition, depending on the way the process is conducted, a solvent is used as cosolvent that must be separated out again. In addition, the described process is a batch process that therefore has a poorer space-time yield than continuous processes.
Another process that is known for the production of powdery particles from fatty masses is the process described in EP 0744992 B1, “Particles from Gas-Saturated Solutions” (process PGSS) in which a certain amount of supercritical fluid is dissolved in a melted mass. The mass with the supercritical fluid dissolved in it is then expanded, during which the mass cools down by the expansion below the melting point of the substance to be treated and a powdery substance is obtained. However, the use of the PGSS process for treating cocoa butter results primarily in the undesired βVI form, as results from “High Pressure Process Technology: Fundamentals and Applications”, section 9.8.7.2 “Cocoa butter”, page 603 to 604, Industrial Chemistry Library, volume 9 (2001).
Another process known for the production of seed crystals is the apparatus of the “Seedmaster” as it is described by Böhler in “Lebensmittel-Industrie” No. 3 to 4, 2005, pages 6 to 7. In this process an additional apparatus is integrated into the system for the production of chocolate in which apparatus cocoa butter crystals are produced on site as seed crystals. These crystals are then fed directly from the apparatus into the system for the production of chocolate. As a result, a continuous process for the production of seed crystals can be made available. The disadvantage of this process is the fact that additional apparatuses must be installed in the system for the production of chocolate and the spatial separation of the production of seed crystals and the production of chocolate is not possible since the seed crystals obtained do not have sufficient stability for this. Furthermore, the maximally achievable solid content in the form of cocoa butter crystals is limited in this process and is approximately 12% m/m, so that the predominant component is liquid cocoa butter, which results in problems conditioned by the recipe.
WO 98/30108 A2 relates to a process for processing chocolate and chocolate products that comprises the use of crystallization nucleators in order to make stabile fatty crystals available in a chocolate without injecting the crystallization of the liquid fatty phase. The addition of the seed crystals takes place above the solidification temperature, as a result of which the crystallization of the fatty phase is shifted to the final cooling off, which has a significant influence on the processing possibilities. Chocolate can be obtained in this manner that has significantly lower fat contents than is usual. The extent of the crystallization in the fatty phase is reduced, during which the crystallization nucleators do not melt. Therefore, the processing range of the chocolate is selected between the chocolate solidification temperature and between the melting temperature of the crystallization nucleators. Preferably, crystals in the βV and βVI forms are present in the hardened chocolate product in the fatty phase. The production of seed crystals is not described.
The article by Braun et al., “Selective precrystallization: a revolutionary process”, ZSW—Zucker—Süsswaren Wirtschaft: Fachzeitschrift für alle Bereiche der Süsswaren-Industry (that is, “Professional Journal for All Areas of the Confectionary Industry”), Beckmann Verlag GmbH & Co. KG, Jan. 1, 2002 describes a precrystallization process in which chocolate mass is precrystallized by being seeded with a crystal suspension of cocoa butter. In the process cocoa butter is melted in a tank at approximately 40 to 50° C. and subsequently shear-crystallized at a cooling-water temperature of 5 to 15° C. The sheer-crystallized cocoa butter is supplied to retained cocoa butter. The mixing takes place at a cooling-water temperature of 24 to 28° C., during which the mixture is held at this temperature for approximately 100 minutes. Primarily crystals in the βVI modification are obtained as seed crystals.
Also, US 2005/049426 A1 describes a process and an apparatus for the production of seed crystal suspensions based on a fatty melt, which process serves in particular to produce microdispersed crystal suspensions of cocoa butter with high βV—modification component. The seed crystallization of fat-based suspensions containing dispersed solid particles such as chocolate masses and chocolate-like masses or the like is described as a use for the crystal suspensions of cocoa butter, whereby the melt is seeded with the crystal nuclei suspensions.
DE 197 48 069 A1 relates to a process for the cooling down and atomizing of liquid or pastry substances or substance mixtures in which a liquid or pastry substance or such a substance mixture is combined with liquid or supercritical carbon dioxide and the mixture of liquid or pasty substance/substance mixture and liquid or supercritical carbon dioxide is subsequently expanded.
US 2005/082701 A1 describes a process and an apparatus for particle formation in which a supercritical fluid is used in the process. In a first step the material from which fine particles are to be formed and the supercritical fluid are mixed with one another in a first chamber. The mixture is melted. In a second step the melt is transferred into a second chamber, more supercritical fluid is added before the mixture of the low-viscosity melt is expanded into an expansion chamber, which expansion chamber has a pressure below the critical pressure of the supercritical fluid in order to convert the supercritical fluid into a gas and to separate the material in particle form. Biologically active materials such as peptides and insecticides and biologically degradable polymers, e.g., polycaprolactone, are cited as material from which particles are to be formed. This process and the previously cited processes do not supply any or only low amounts of βVI crystals in the production of seed crystals from cocoa butter.
WO 2009/005346 A1 describes a method for the production of particles in the food area from a lipid and a water-soluble active substance that comprises the dispersing or emulsifying of the active substance in the lipid, the following mixing with a supercritical or gaseous medium and the spraying of the mixture. Reaction conditions under which an especially advantageous crystallization form is obtained are not named.
EP 0 521 205 A1 describes a process for using seed crystals for the production of tempered confections. The process provides that a continuous addition of crystal nuclei to the liquid confection composition takes place in the form of a suspension. Continuously operating systems are associated as a rule with greater investment costs than discontinuous systems. The process according to EP 0 521 205 A1 requires that the apparatus for the continuous addition of the crystal nuclei is directly coupled to the system for the production of chocolate; thus, additional apparatuses are also required here in the system for the production of chocolate.